In general, prior art telecommunications switching system, that provided wireless service for mobile units, have not allowed for the portability of features from one switching system to another. Within the wireless prior art, it is known to be able to go from one geographical area served by one switching system to another geographical area served by another switching system and to be able to register a mobile unit in both geographical areas. In addition, the U.S. patent application entitled "Telecommunication Switching System Having Transparent Wireless Features", Ser. No. 08/371,652, a Continuation of Ser. No. 07/995,417 filed Dec. 8, 1992, now abandoned, discloses the sharing of a telephone number by a wireless mobile unit and a stationary telephone station set. In the referenced patent application, the features provided to the mobile unit are the same and appear to be performed on the switching system to which the stationary telephone station set is attached regardless to which switching system the mobile unit is registered. The referenced patent application also allows for the same type of operations without requiring a stationary telephone station set be associated with the mobile unit. In this case, the wireless mobile unit is assigned a home switching system, and all feature actuations appear to occur on this home switching system. The referenced U.S. patent application does solve the problem of allowing coordination of features between the stationary telephone station set and the wireless mobile unit.
The problems in the prior art are as follows. First, whether the wireless mobile unit is associated with a stationary telephone station set or not, the user of the wireless mobile unit may want some of the telecommunication features provided to the wireless mobile unit to always function as if the wireless mobile unit was registered on the home switching system; whereas, other telecommunication features are to function as if the mobile unit was a stationary telephone set attached to the temporary switching system. As examples, the voice mail system utilized by the user of the mobile unit may remain fixed and be associated with the permanent switching system. The user of the mobile unit would be able to access the voice mail messages as if the mobile unit was registered on the permanent switching system. However, the fax machine associated with the wireless telephone should be at the location of the switching system to which the wireless telephone set is presently registered. Another example of a feature which may remain fixed with respect to the permanent switching system is call coverage provided to the mobile unit regardless of where the unit is. Finally, greater flexibility must be allowed the users of mobile units in determining which features will appear to be provided by the permanent switching unit and which features will appear to be provided by the switching system on which the mobile unit is presently registered.